Composite sheet



H. S. LEWIS.

COMPOSITE SHEET.

APPLIATION FILED ocT.2o, 1919.

1,374,931. Patenta& Apr. 19, 1921.

%wwi/WWW WWWWWW UNITED 'STATES PATEN'I' OFFICE.-

s eoncaton ot Letters Patenta Patented Apr. 19, 1 921.

Application filed October 20, 1919. Serial No. 38,965.

To all whom it may coment: I

Be it known that I, HARRY S. Lnws, of Beaver F alls, in the county of Lews, in the State of New York, have nvented new and useful Improvement-,s in Composite Sheets, of which the following, taken in connecton with the accompanying drawings, s a full, clear, and exact descrpton.

This invention relates to certain mprovements in a composite sheet, capab1e of use for various purposes, but peculiarly desi ed and adapted for use as wall board.

he manufacture of wall board, as practised today, consists of building up, by the use of suitable adhesive, two or more plies of so-called wood pulp board manufactured from either ground wood pulp or from socalled paper stock board manufactured from waste papers, each ply being usually from .030 to .055 of an'inch in thickness according to the number of plies' desired for a certain desired thickness of-the finished product, such product being usually from to of an inch thick.

Some grades of wall board are at present made entirely of board manufactured from ground wood pulp made from soft wood, such as spruce, balsam, hemlock, pne and poplar wood, while other manufacturers, to reduce the cost of production, use n the finished product center 'plies of board manufactured from old paper stock, which board commands much lower price in the market than that manufactured direct from the ground wood pulp, but the combined or finished board frequently lacks the rigidity and strength of the wall board manufactured from all fresh ground wood pulp.

Rigidity is the characteristc of greatest importance in connection with the product known as wall board and I have experimented extensively in an efi'ort to produce a wall board of greater rigidity and strength as compared with the commercial wall board made today. My experments have lead to a development quite remote from the present day manufacture of wall board and to the use of material heretofore considered imprac'tical for that purpose, viz: the use of ground wood made from hard wood, such as beech, birch, maple, elm, Chestnut, oak, etc., adequately steamed or boled prelimnar to grinding. p

y early experiments demonstrated that when hard wood was ound in the usual manner of grnding so wood for the producton of wood pulp, a product was obtaned which was of very short fiber amountng to practically a wood flour, having very little strength, impractical for handling on a paper machine without admxture of other stock and commercially useless for the purpose at hand.

I have found, however, that if hard wood s properly and adequately steamed or boled prior to grinding n the usual manner of grinding wood pulp, that a wood pulp is *produced which when manufactured into board has the desired characteristic of unusual rigidity and strength.

Therefore, in the process of manufacturin wood pulp from hard wood, the wood is o su jected to steaming and boilin preliminary to grinding and purely as i lustrative of a suitable operation of that character the wood in a closed chamber may be subjected to the action of steam under pressure as, for instance, fifty pounds for a period of eighteen hours. formed into single ply in the usual manner of treating soft wood pulp.

The composite wall board is then built up of any desired number of plies or laminations of board consisting of or comprising wood pulp manufactured from hard wood. Or perhaps preferably the center plies may be formed of such board manufactured from wood pulp produced from hard wood and the outer or facing plies or laminations may be formed of the ordinary commercial wood pulp board manufactured from soft woods so that the composite board has a substantially white or rayish-white surface color characteristic of natural wood pulp manufactured from the soft woods and the center plies or laminations are of the brown or dark brown color found characteristic of wood pulp produced by grinding hard wood after steaming or boiling. he advantages ofths are at least twofo First, the resultant product has a materially increased rigidity and stren h, and

Second, the product can be pro uced at a much cheaper cost by reason of the availability and the relatively low price of hard wood for the manufacture of wood pulp.

I, therefore, claim as new and original,

It is then ground and the manufacture of a composite or built-up sheet suitable for wall board or other purpose, the center plies of which, or all or any of the plies of which, consist of o'r contain a desired percentage of pulp made from the woods known as hard, after such woods have been steamed or boiled as hereinbefore described, thereby increasing the rigidity and` strength and decreasin the cost of production of the complete board as compared with the wall board of commerce as made today.

i In the manufacture of the single plies of board which are afterward laminated or built up into the'plural ply or finished wall board, a single ply sheet or web s bult up on the so-called board machine in two or more layers by the use of two or more cylinders, these layers adhering to each other because of the pressure exertedupon the web while it is still in a moist state. In this manner it is possible to manufacture a web or sheet of single ply board for use as the two outside plies, sheets or laminations for the finished composite board, with as many cylinders as desired runnin on the pulp produced from steamed or boiled hard wood and with one or more cylinders running on pulp of other character, such as that produced from soft Woods, so that the finshed single ply sheet may consist of any de sired number of layers formed from wood pulp manufactured from hard wood and any desired number of la ers formed from wood ?pulp manufactured rom soft wood or other material and the finished single ply sheet may, therefore, have any desired shade or color upon either or both sides while the center or either or both sides may consist entirely of board containing any percentage desired of the pulp made from the steamed or boiled hard wood of characteristic brown color.

In the drawings, I have illustrated various forms that my invention may take.

Figure 1 is an elevation of a sample of Wall board manufactured in accordance with my invention.

Fig. 2 is a vertical section. of the same.

Figs. 3 and 4: are vertical sections of modified constructions of Wall board made in accordance with my invention.

In Fig. l, I have shown a wall board consisting of five plies, laminations, or sheets, numbered 1, 2, 3, 4: and 5, respectively. The plies 1 and 5 are formed of the usual board manufactured from wood pulp produced from soft wood or other material and are of the grayish-white color characteristic of board so manufactured, while the three inner plies, numbered 2, 3 and 4, are of the brown color found characteristic of board manufactured from pulp produced from hard wood after the same has been steamed or boiled. The five sheets or plies are united by any suitable adhesive or cement, such as silicate of soda, to constitute a relatively ri id unitary composite sheet.

ig. 2 illustrates a vertical section of the composite wall board of F ig. 1.

F 3 illustrates a composite wall board in w ich each and all of the single ply sheets, numbered 10 to 14, inclusve, and united to form the composite board, are formed from wood pulp or embody a percentage of wood pulp manufactured from steamed or boiled hard wood. While this Construction may have certain advantages over the Construction of Fig. 1, it, nevertheless, has this disadvantage, viz: The completed board is of the brown color characteristic of wood pulp manufactured from hard wood after steaming or boiling, while for many purposes a much lighter color is desirable as, for instance, the grayish-white uolor characteristic of wood pulp manufactured from soft wood. For the purpose of giving the desired color to the external surfaces of the wall board, while utilizing as much hard wood pulp as possible in the completed board, I have disclosed the construction of Fi 4.

This figure lustrates a composite board in which the three central sheets or plies consist of or comprise wood pul manufactured from steamed or boiled ard wood, while the outer sheets, 6 and 7, each consist of a single ply embodying an outer layer or series of layers 8- formed of wood pulp made from soft wood or other material, and an inner layer orseries of layers 9- formed of or embodyng wood pulp manufactured from steamed or boiled hard wood. These outer sheets, 6 and 7, are manufactured on the usual and well known board machine with as many cylinders as desired running on pulp produced from steamed or boiled hard wood, and one or more cylinders running on pulp produced from soft wood or other material, producing a single ply or sheet consisting of a plurality of layers in the usual manner.

It will be understood that a ercentage of soft wood pulp or paper stoc pul or other material may be added to the ard wood pulp during the heating or mixing process with perhaps somewhat less advanta geous results and that the composite board may be formed of any desired number of plies or laminations and that such laminations, plies or sheets may be Secured together in any suitable manner and that each sheet may consist of, or comprise, any desired percentage of wood ulp manufactured from hard wood cooked y the steaming or boiling process, and that various modifications may be made in the details of the process and the product all without departing from the invention as set forth in the appended claims.

What I claim is:- 4

1. A laminated board suitable for wall board or other purposes, the center plies of which include Wood pulp manufaetured from 5 ground cooked hard wood and the outer plies of which include pulp manufactured from other material.

2. A laminated board having a central ply consisting of ground, cooked, hard wood,

and tWo facing ples consisting of pulp mad from different material.

3. Wall board comprising a sheet of ground, cooked, hard Wood pulp faced on both sides With soft wood pulp.

4. Wall board comprising a relatively rigid layer of ground, cooked, hard wood pulp having a less rigid facing of soft wood u p 5?A laminated board suitable for wall board or other purposes, comprising a relatively rigid layer consisting substantally of Wood pulp manufactured from ground, cooked hard wood, and a less rigd facing layer consisting of pulp manufactured fro other material.

In witness Whereof I have hereunto set my hand this 16th day of October, 1919.

HARRY S. LEWIS.

Witnesses:

H. E. CHASE, E. A. THoMPsoN. 

